Atari Megafile General Maintenance
Care, opening and internal checks for the Atari Megafile hard disk drives, the Atari Megafile 30 and Atari Megafile 60. The two models share an owner's manual and a controller drawing, so one guide covers both.[1][2] Atari's own maintenance advice stops at the outside of the case; the internal notes below come from Atari's controller schematic, drawing C103166, and from owners' repair reports, which are named where they are used.
Warning: the drive contains a mains power supply. Atari's manual says not to remove the housing because of the risk of electric shock and of damage to the drive and computer.[3] Unplug the mains lead before opening the case, and treat the supply's primary side as live until its capacitors have discharged.
Regular care
[edit | edit source]Atari's preventive maintenance list in appendix A of the owner's manual:[3]
- Keep the drive and computer on a sturdy, level surface, away from dust, grease, extreme temperatures, direct sunlight and moisture.
- Do not smoke near the system, and keep liquids away from it.
- Switch the system off before cleaning, and clean only the outside with a soft, slightly damp, lint-free cloth. Do not use cleansers, abrasives or solvents.
- Park the heads with the HDX Ship option or SHIP.PRG before moving, shipping or storing the drive.
Leave room for air to flow round the drive, and do not slide papers between the Megafile and a computer stacked on it; Atari warns that this blocks the vents of the internal cooling system.[4] One owner who opened his Megafile 30 to clean it found years of dust inside.[5]
Switching on and off
[edit | edit source]Switch the Megafile on before the computer. The busy light on the front blinks briefly and the drive spins up; when the light goes out and the whirring stops, switch on the other peripherals and then the computer. To shut down, switch off the computer first, then the drive.[4] Atari's specification gives a typical 22 seconds from power-up to ready and 20 seconds for the disk to stop after power-down, so wait that long before moving the drive or switching it on again.[1]
Parking the heads
[edit | edit source]Atari supplies two head-parking programs on the Hard Disk Utilities disk. Both run from floppy only.[6]
- Close every window on the hard disk drives.
- To park every drive on the chain, run SHIP.PRG from the HDX folder, and switch the drives off as soon as the GEM desktop reappears.
- To park chosen drives, run HDX.PRG, select Ship from the Disk menu, select the units, confirm the two warnings, and switch those drives off when told to.
The heads unpark by themselves the next time the drive is switched on. Atari warns that parking with a hard disk window still open can damage data.[6]
Checking the disk surface
[edit | edit source]Atari tells owners to check the disk for bad sectors periodically, noting that it is normal for defective spots to appear after the drive has been in use for a while. The HDX Markbad option scans one logical drive and lets you decide what to do with each damaged file; the Format option runs Markbad across the whole unit and erases everything on it.[7] Back up before either.
Owners report that the Seagate ST-238R drives in these units lose data over time and work again for a while after a fresh low-level format, and one owner's Megafile came back with two bad sectors after reformatting.[8] Formatting with HDX erases the whole drive.[9]
Inside the drive
[edit | edit source]Opening the case
[edit | edit source]Atari published no disassembly procedure for the Megafile 30 or 60. In December 1989 ANALOG Computing printed one for the Megafile 20 when fitting a new mechanism: park the heads, place the drive upside down on a cloth, remove the nine gold-coloured screws from the bottom (leaving the four silver screws that hold the drive mechanism), turn it over and lift the case off the base, then straighten the eight tabs that hold the RF shield and lift the shield away to reach the controller board, power supply and drive.[10] Check your own unit against this before relying on it; the article describes the earlier MFM model.
Power connectors and voltages
[edit | edit source].png)
On drawing C103166 the supply connects to the controller board at J5: +5 V on pins 1 and 2, ground on pins 3 to 5 and +12 V on pin 6. The board passes both rails to the drive mechanism through J9 and +12 V to the fan through J8.[2] With the drive running, measure between ground and the +5 V and +12 V pins of J5, or at the drive's own power plug. Atari does not print a tolerance for either rail.
Capacitors
[edit | edit source]The controller drawing shows three electrolytic capacitors, all 10 µF, with no voltage rating printed for any of them:[2]
| Ref | Value | Where it sits on the drawing |
|---|---|---|
| C5 | 10 µF | 8085 (U7) reset input, pin 36, with R5 (27 kΩ) and CR1 (1N4148) |
| C47 | 10 µF | +12 V feed from J5, beside C51 (0.1 µF) |
| C48 | 10 µF | +5 V feed from J5, beside C49 (0.01 µF) |
Read the rating off the fitted part before ordering a replacement. On the C100169 board found in some Megafile 30s, one owner replaced a tantalum bead capacitor at C27 marked "106L", which forum members read as 10 µF, with a 10 µF 50 V part.[5]
None of the Megafile documents on Atari Megafile Documentation covers the power supply. In 2005 an atari-forum member advised resoldering the supply, replacing all of its electrolytic capacitors and checking the rails with an oscilloscope, because a supply can read 12 V and 5 V on a meter and still carry ripple.[11] A member of AtariAge suggested in 2017 that failed capacitors in the supply were the likely cause of a dead Megafile 60.[12] See Capacitor Failure Symptoms for what to look for.
Unit number switch
[edit | edit source]The unit number is set by SW1, a three-position switch on the controller board read by the 74LS85 comparator U18.[2] Every Megafile leaves the factory as unit 0, and a drive that has never been formatted must be set to unit 0 for HDX to format it. A second drive on the chain needs a different number.[4][9]
Fan
[edit | edit source]The fan runs from +12 V on J8.[2] Check that it turns when the drive is switched on. One owner's Megafile 30 worked for about 30 minutes and then became too hot to read anything.[8]
Replacing the drive mechanism
[edit | edit source]Original RLL mechanisms are now scarce and expensive, and owners on atari-forum and AtariAge advise against relying on a used one.[8][13] If you do fit one, HDX must be given the drive's exact geometry. An atari-forum member warned in 2012 that a wrong cylinder count can drive the heads beyond the end of their travel, and Atari's error-message appendix warns that modifying the WINCAP parameter file may destroy the disk.[8][14]
The other choices owners use:
- An MFM drive emulator in place of the mechanism, such as the designs from pdp8online.com and decromancer.ca. In 2024 these cost about US$200 to US$250.[13]
- A SCSI host adapter in place of the Megafile controller, driving a SCSI disk or an SD card adapter. One owner put a Link adapter and a SCSI drive in his; another planned an ICD AdSCSI board with a SCSI2SD.[13][8]
A low-level format, or leaving the drive running for an hour, has also revived drives that owners had written off; see Atari Megafile Troubleshooting Guide before replacing anything.[13]
Related pages
[edit | edit source]- Atari Megafile 30
- Atari Megafile 60
- Atari Megafile Troubleshooting Guide
- Atari Megafile Documentation
- Hard Drive Maintenance and Repair
- Capacitor Failure Symptoms
- Recommended Tools
References
[edit | edit source]- ↑ 1.0 1.1 Atari Corporation, MEGAFILE Hard Disk Drive Owner's Manual, C300459-001 Rev. B, 1988, appendix C, pp. 53-54: specifications for the Megafile 30 and 60, start and stop times.
- ↑ 2.0 2.1 2.2 2.3 2.4 Atari Corporation, Schematic Diagram, Megafile 60 (RLL), drawing C103166 Rev. 4, drawn 23 March 1988, in Schaltungsdienst Lange, Megafile 30, Megafile 60 Service Manual, PDF pp. 2-3: J5, J8, J9, C5, C47, C48, SW1 and U18. Hosted as File:Atari Megafile 30 and 60 Service Manual (Schaltungsdienst Lange).pdf.
- ↑ 3.0 3.1 Atari Corporation, MEGAFILE Hard Disk Drive Owner's Manual, C300459-001 Rev. B, 1988, appendix A, "Preventive Maintenance", p. 45 (PDF p. 47).
- ↑ 4.0 4.1 4.2 Atari Corporation, MEGAFILE Hard Disk Drive Owner's Manual, C300459-001 Rev. B, 1988, chapter 1, pp. 3-7 (PDF pp. 7-11): air vents, DIP switches and unit numbers, switching on and off. Hosted as File:Atari Megafile Owner's Manual C300459-001 Rev B.pdf.
- ↑ 5.0 5.1 AtariAge Forums, "Megafile capacitor replacement", August 2022: dust build-up, the C27 tantalum on an SH205 C100169 Rev. 5 board in a Megafile 30. Forum thread.
- ↑ 6.0 6.1 Atari Corporation, MEGAFILE Hard Disk Drive Owner's Manual, C300459-001 Rev. B, 1988, pp. 31-34 (PDF pp. 33-36): parking and unparking the drive heads.
- ↑ Atari Corporation, MEGAFILE Hard Disk Drive Owner's Manual, C300459-001 Rev. B, 1988, pp. 34-39 (PDF pp. 36-41): marking bad sectors.
- ↑ 8.0 8.1 8.2 8.3 8.4 atari-forum.com, "Atari MegaFile Hard Drive Replacement", October 2006 to January 2023: RLL replacements and geometry (Lando_C, 2012), ST-238R data loss and low-level formatting (tzok and rcamp48, 2023), a Megafile 30 that fails when hot and an ICD AdSCSI plan (jd, 2023). Forum thread.
- ↑ 9.0 9.1 Atari Corporation, MEGAFILE Hard Disk Drive Owner's Manual, C300459-001 Rev. B, 1988, pp. 12-17 (PDF pp. 15-20): running HDX and formatting; an unformatted drive must be set to unit 0.
- ↑ Gregg Anderson, "Massaging Your MegaFile", ANALOG Computing issue 79, December 1989, p. 114: opening the Megafile 20 and fitting a new drive.
- ↑ atari-forum.com, "megafile 30 problem - clicking noises!", post by simbo, 27 November 2005: resoldering and recapping the power supply, checking the rails with an oscilloscope. Forum thread.
- ↑ AtariAge Forums, "Install Megafile 60", January 2017. Forum thread.
- ↑ 13.0 13.1 13.2 13.3 AtariAge Forums, "Two dead Megafile 30s, options for MF drives", April 2024: MFM emulators and their price, an ICD Link conversion, drives revived by low-level formatting or by running for an hour. Forum thread.
- ↑ Atari Corporation, MEGAFILE Hard Disk Drive Owner's Manual, C300459-001 Rev. B, 1988, appendix B, p. 47 (PDF p. 48): "Do not modify the WINCAP file. Doing so may destroy the disk."